低温胁迫对2个茶树品种叶片叶绿素荧光特性的影响

以茶树〔Camellia sinensis ( Linn.) O. Ktze.〕品种‘黄金芽’(‘Huangjinya’)和‘迎霜’(‘Yingshuang’)为实验材料,研究了4℃低温胁迫1、2、4和6d对茶树叶片叶绿素荧光特性的影响。结果表明：4℃低温胁迫条件下2个茶树品种叶片的PSⅡ最大光化学效率( Fv/Fm )、PSⅡ潜在活性( Fv/F0)和表观光合电子传递速率( ETR)均显著低于各自的对照(25℃),且总体上随胁迫时间延长逐渐下降;‘黄金芽’叶片的光化学淬灭系数(qP)随低温胁迫时间延长持续下降且低于其对照,而‘迎霜’叶片的qP较其对照的变幅较小,且2个品种的qP总体上与各自的对照无显著差异;随低温胁迫时间延长,2个品种叶片的非光化学淬灭系数( NPQ)均先升高后降低,并在胁迫2 d时达到最高,且总体上高于各自的对照;而2个品种叶片的光合功能相对限制值( LPFD )均随低温胁迫时间延长而增大,且大多高于各自的对照。与各自的对照相比,低温胁迫条件下‘迎霜’叶片的各项叶绿素荧光参数的变幅总体上低于‘黄金芽’。研究结果显示：低温胁迫可直接损伤茶树叶片的PSⅡ反应中心,致使过剩的激发能大量积累于PSⅡ反应中心,最终导致茶树光合作用能力减弱。根据叶绿素荧光参数的比较结果,可以初步判定品种‘迎霜’的耐寒性优于品种‘黄金芽’。     

大气CO2浓度倍增和施氮对冬小麦光合及叶绿素荧光特性的影响

采用开顶式气室,通过土培盆栽实验研究了不同大气CO2浓度(背景空气浓度375μmol·mol-1和倍增浓度750μmol·mol-1)和氮素水平(不施氮和施氮0.25 g/kg)下两个冬小麦品种(小偃6号和小偃22)主要生育期(拔节、孕穗、扬花、灌浆期)叶片叶绿素含量和荧光动力学参数的变化.结果显示,与背景CO2浓度相比,在不施氮条件下大气CO2浓度倍增处理的小麦叶片出现明显的光合下调现象,而施氮时变化不明显;同时,CO2浓度倍增后小麦各主要生育期叶片叶绿素含量均有不同程度地下降,荧光参数初始荧光(F0)值明显提高,最大荧光(Fm)、可变荧光(Fv)、最大光能转换效率(Fv/Fm)和PSⅡ潜在活性(Fv/F0)值均显著降低.施氮可提高冬小麦各个时期叶片叶绿素含量、Fm、Fv、和Fv/F0值,降低F0值;不施氮条件下,大气CO2浓度倍增对冬小麦各主要生育时期叶绿素含量和荧光参数的影响明显,而施氮后影响微弱.研究表明,大气CO2浓度升高对冬小麦光合速率、叶绿素含量和光系统Ⅱ(PSⅡ)的光合电子传递和潜在活性具有一定抑制作用,通过施氮可以有效地缓解其负面效应.     

土壤氮磷化学计量特征对小麦光合气体交换参数和叶绿素荧光参数的影响

选取‘镇麦168’为实验对象,采用盆栽实验,设置16个不同土壤氮磷梯度,测定不同土壤氮磷化学计量比处理下小麦叶片叶绿素含量、光合气体交换参数和叶绿素荧光参数的响应特征,以揭示不同土壤氮磷化学计量关系对小麦叶片光合特性影响的生理生态机制。结果表明:(1)不同生育期内小麦叶片叶绿素含量均随土壤速效N或速效P含量的增加而增加。(2)随着土壤化学计量比N∶P下降,小麦叶片净光合速率(Pn)在土壤中低氮水平(≤258.4mg·kg~(-1))下持续增加,在高氮水平(308.4mg·kg~(-1))下则呈现先增后降的趋势。(3)在土壤速效N相同水平处理下,土壤化学计量比N∶P的降低显著提高了小麦叶片叶绿素荧光参数最小荧光(F0,7.27%~20.00%)、最大荧光(Fm,5.28%~16.15%)、光化学猝灭系数(qP,6.64%~20.92%)及实际光化学效率(ΦPSⅡ,6.95%~18.82%),显著降低了非光化学猝灭系数(NPQ,7.42%~25.63%,P0.05)。研究认为,在中、高氮磷养分水平下,土壤化学计量比N∶P为2.88时,‘镇麦168’叶片净光合速率和实际光化学效率均达到最高水平,表现出较强的光能利用能力。     

外源亚精胺对盐胁迫下黄瓜幼苗光合作用的影响

采用营养液栽培,研究了外源亚精胺对50mmol·L-1NaCl胁迫下黄瓜幼苗植株生长、叶片叶绿素含量、光合气体交换参数和叶绿素荧光参数(PSⅡ光化学效率)的影响。结果表明:NaCl胁迫显著降低了黄瓜植株生长量、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)(P<0.05),但对PSⅡ实际光化学效率(ФPSⅡ)、光化学淬灭(qP)、有效光化学效率(Fv′/Fm′)、非光化学淬灭(qN)和PSⅡ最大光化学效率(Fv/Fm)无显著影响(P>0.05);外源亚精胺显著提高了盐胁迫下黄瓜植株生长量、叶绿素含量、净光合速率、气孔导度、胞间CO2浓度,增加了ФPSⅡ、qP、Fv′/Fm′,降低了qN(P<0.05);外源亚精胺对Fv/Fm影响不显著(P>0.05)。外源施加亚精胺可增强盐胁迫下黄瓜植株的光合能力,主要是由于减弱了盐胁迫对植株的气孔限制,但对PSⅡ实际光化学效率影响较小,且叶面喷施比根施处理对改善盐胁迫下植株的生长和光合作用更有效。     

施氮和大气CO2浓度升高对小麦旗叶光合电子传递和分配的影响

采用开顶式气室盆栽培养小麦,设计2个大气CO2浓度(正常:400 μmol.mol-1;高:760 μmol·mol-1)、2个氮素水平(0和200 mg·kg-1土)的组合处理,通过测定小麦抽穗期旗叶氮素和叶绿素浓度、光合速率(Pn)-胞间CO2浓度(C1)响应曲线及荧光动力学参数,来测算小麦叶片光合电子传递速率等,研究了高大气CO2浓度下施氮对小麦旗叶光合能量分配的影响.结果表明:与正常大气CO2浓度相比,高大气CO2浓度下小麦叶片氮浓度和叶绿素浓度降低,高氮处理的小麦叶片叶绿素a/b升高.施氮后小麦叶片PSⅡ最大光化学效率(Fv/Fm)、PSⅡ反应中心最大量子产额(Fv'/Fm')、PSⅡ反应中心的开放比例(qr)和PSⅡ反应中心实际光化学效率(φPSⅡ)在大气CO2浓度升高后无明显变化,虽然叶片非光化学猝灭系数(NPQ)显著降低,但PSⅡ总电子传递速率(JF)无明显增加;不施氮处理的Fv'/Fm'、φPSⅡ和NPQ在高大气CO2浓度下显著降低,尽管Fv/Fm和qp无明显变化,JF仍显著下降.施氮后小麦叶片JF增加,参与光化学反应的非环式电子流传递速率(Jc)明显升高.大气CO2浓度升高使参与光呼吸的非环式电子流传递速率(J0)、Rubisco氧化速率(V0)、光合电子的光呼吸/光化学传递速率比(J0/Jc)和Rubisco氧化/羧化比(V0/Vc)降低,但使Jc和Rubisco羧化速率(Vc)增加.因此,高大气CO2浓度下小麦叶片氮浓度和叶绿素浓度降低,而增施氮素使通过PSⅡ反应中心的电子流速率显著增加,促进了光合电子流向光化学方向的传递,使更多的电子进入Rubisco羧化过程,Pn显著升高.     

氮素水平对茶树叶片氮代谢关键酶活性及非结构性碳水化合物的影响

以福鼎大白茶(FD)、保靖黄金茶1号(HJ1)、白毫早(BHZ)为材料,设置不施氮N_0(0 g)、低氮N1(11 g)、中氮N_2(22 g)和高氮N_3(33 g)4个氮素水平的盆栽实验,研究了铵态氮对3个品种茶树的根系活力、氮代谢关键酶及非结构性碳水化合物(NSC)的影响。结果表明:随着施氮水平的提高,N_2、N_3处理的茶树根系活力较对照N0显著增加(P0.05),但二者间无显著差异;叶片谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)活性总体呈上升趋势;与对照比较,茶树叶片全氮和可溶性蛋白含量增加,其中HJ1在N_2和N_3处理后显著增加(P0.05);在3个茶树品种中,非结构性碳水化合物中可溶性总糖含量均呈上升趋势,淀粉含量具有品种特异性,施氮处理后3个茶树品种氮代谢关键酶活性及NSC含量变化存在差异,以HJ1的氮同化关键酶GS、GOGAT酶活性较高、根系活力较强,氮代谢产物显著增加,表明其具有较高的氮同化速率。施氮后HJ1的总NSC的含量及碳氮比的变化幅度较另外2个品种小,能够更好的保持碳氮平衡,游离氨基酸含量增幅较高,品质更优。因此,通过茶树氮代谢关键酶活性及非结构性化合物的研究能为茶树品种的品质评价以及提高茶树的品质和氮素利用效率提供依据。     

复水对旱后不同玉米品种植株生长恢复能力及其生理响应特性的影响

该研究选用2个抗旱能力相似但旱后恢复能力存在显著差异的玉米品种‘P3’和‘郑单958’为材料,采用盆栽称重控水法在苗期进行干旱及复水处理,通过测定其生长、水分状况、光合参数、叶绿素荧光参数以及叶绿素含量在干旱及复水过程中的变化规律,探讨干旱及复水过程中生理生化响应与旱后恢复能力的关系。结果发现:(1)抗旱性相同的2个玉米品种在干旱复水后的生长恢复能力表现为‘P3’显著强于‘郑单958’。(2)干旱胁迫后,‘郑单958’和‘P3’的叶片相对含水量差异不显著,但‘P3’能维持较高的叶水势、PSⅡ最大光化学效率和叶绿素含量。(3)经干旱胁迫复水后,‘P3’的净光合速率,PSⅡ最大光化学效率和气孔导度恢复速度快于‘郑单958’,说明‘P3’光合损失恢复能力高于‘郑单958’。研究表明,玉米品种‘P3’的旱后复水生长恢复能力较强,因‘P3’在干旱胁迫下能维持较高的Fv/Fm值和叶绿素含量,光系统的损伤较轻,而且复水后也能较快的恢复;在干旱过程中减轻干旱胁迫对植物光合系统的伤害是旱后复水快速恢复生长的基础,而在复水后快速修复光系统损失能够加快植物复水的恢复速度。     

紫花苜蓿叶输导组织解剖结构和光合特性对外源氮的响应

以紫花苜蓿品种‘甘农3号’和‘陇东苜蓿’为研究材料,采用室外(防雨网室)盆栽营养液砂培法,研究了2种氮素形态(NO3--N,NH4+-N)的5个氮素水平(0、105、210、315、420mg·L-1)处理对叶片输导组织解剖结构及光合特性的影响。结果显示:(1)与无氮处理相比,供氮处理下‘甘农3号’和‘陇东苜蓿’输导组织的解剖结构和光合特性发生明显变化,叶片输导组织维管束、木质部和韧皮部面积显著增大,导管数显著增多,净光合速率、气孔导度、叶面积和叶绿素含量均显著增加,且在210mg·L-1供氮水平下达到最大值。(2)2种氮素形态相比,‘甘农3号’和‘陇东苜蓿’叶片输导组织维管束面积、木质部面积、韧皮部面积、导管数、净光合速率、气孔导度、叶面积、叶绿素含量均表现为NH4+-N处理好于NO3--N处理。(3)2品种相比,叶片输导组织维管束面积、木质部面积、韧皮部面积、导管数、净光合速率、气孔导度、叶面积、叶绿素含量表现为‘甘农3号’大于‘陇东苜蓿’。研究表明,氮素能通过改善紫花苜蓿叶片输导组织的解剖结构和光合特性,促进紫花苜蓿光合作用;各处理中以NH4+-N、210mg·L-1表现最佳,维管束面积最大,木质部、韧皮部面积大且发育好,导管数最多,而且‘甘农3号’表现更优。     

水肥运筹对小麦旗叶光合特性及产量的影响

研究了不同灌水次数及等氮量不同施氮方式对优质强筋小麦品种郑麦9023旗叶净光合速率(Pn)、叶绿素荧光参数等光合性能及产量的影响。结果表明,旗叶Pn、PSⅡ的潜在活性(Fv／Fo)、PSⅡ的光化学最大效率(Fv／Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(qN)及产量在不同灌水次数间的差异均达到显著或极显著水平,其中不灌水处理与灌水处理间的差异较大;在不同施氮处理问,氮肥全部基施与返青期追施(占40％)处理间植株旗叶的Pn、Fv／Fo、Fv／Fm、qP和qN差异不大,但两处理的上述光合参数及产量均明显低于拔节期或孕穗期追施(40％)处理,表明拔节期或孕穗期追施氮肥有助于减缓旗叶光合功能的衰退,延长叶片功能期,提高植株的光合产物积累。研究结果还表明,水、氮运筹对Pn、叶绿素荧光参数及产量性状的调控存在显著的互作效应,其中以灌拔节水 孕穗水并于孕穗期追施氮肥(W2N4)处理组合表现最好。     

干旱胁迫下转ClNAC9基因露地菊品种‘纽9717’叶片光合及叶绿素荧光特性的比较

对干旱胁迫0~15 d露地菊(Chrysanthemum morifolium Ramat.)品种‘纽9717’(‘Niu 9717’)野生型和3个转ClNAC9基因株系(ClNAC9-5、ClNAC9-6和ClNAC9-13株系)叶片的叶绿素含量、光合参数和叶绿素荧光参数进行了比较和分析。结果表明:干旱胁迫0~15 d,野生型和3个转ClNAC9基因株系叶片中叶绿素含量总体上呈先升高后降低的变化趋势。与干旱胁迫0 d相比较,除初始荧光(F_o)和非光化学淬灭系数(qN)外,干旱胁迫15 d时3个转ClNAC9基因株系叶片的叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、水分利用效率(WUE)、最大荧光(F_m)、可变荧光(F_v)、PSⅡ最大光化学效率(F_v/F_m)、PSⅡ潜在光化学活性(F_v/F_o)和光化学淬灭系数(qP)的降幅均小于野生型。总体上看,干旱胁迫15 d,3个转ClNAC9基因株系叶片的叶绿素含量、Pn、Gs、Tr、WUE、F_m、F_v、F_v/F_m、F_v/F_o、qP和qN值显著高于野生型,而F_o值显著低于野生型。研究结果显示:将ClNAC9基因转入露地菊品种‘纽9717’可以增强该品种对干旱胁迫的耐受性,其中,ClNAC9-5和ClNAC9-6株系对干旱胁迫的耐受性较强,ClNAC9-13株系对干旱胁迫的耐受性较弱,但均强于野生型。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

广西青藓科分类学修订

通过对采自广西24个县(市)的1 147份青藓科植物标本的逐一鉴定及相关文献的查阅,确认有广西青藓科植物11属、44种,其中包括广西青藓科植物新记录属1属,即拟异叶藓属(Pseudokindbergia),新记录种7种,分别为匐枝青藓(Brachythecium procumbens)、阔叶尖喙藓(Oxyrrhynchium latifolium)、泛生尖喙藓(O. vagans)、拟异叶藓(Pseudokindbergia dumosa)、华东细喙藓(Rhynchostegiella sinensis)、长肋拟青藓(Sciurohypnum populeum)和弯叶拟青藓(S. reflexum)。该文提供了修订后的广西青藓科植物名录,并对其中的新记录属、种的主要形态学识别特征、生境和地理分布等进行了详细描述。     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

Evaluation of antiprotozoal and antimycobacterial activities of the resin glycosides and the other metabolites of Scrophularia cryptophila

Resin glycosides are secondary metabolites exclusive to the convolvulaceous plants. In this study, crypthophilic acids A–C (1–3), the first resin glycosides occurring in another family (Scrophulariaceae), and the other constituents of Scrophularia cryptophila were examined for in vitro antiprotozoal and antimycobacterial potentials. Except for crypthophilic acid B (2), all tested compounds exhibited growth-inhibitory effect against Trypanosoma brucei rhodesiense, with l-tryptophan (6) and buddlejasaponin III (7) being the most potent ones (IC₅₀'s 4.1 and 9.7 μg/ml). In contrast, the activity towards Trypanosoma cruzi was poor, and only crypthophilic acid C (3), 6 and 7 were trypanocidal at concentrations above 40 μg/ml. With the exception of 2 and 6, all compounds were active against Leishmania donovani. Harpagide (4) and 3 emerged as the best leishmanicidal agents (IC₅₀'s 2.0 and 5.8 μg/ml). Only compounds 3, 6 and 7 showed antimalarial activity against Plasmodium falciparum with IC₅₀ values of 4.2, 16.6 and 22.4 μg/ml. Overall the best and broadest spectrum activity was presented by compounds 3 and 7, as they inhibited all four parasitic protozoa. None of the isolates had significant activity against Mycobacterium tuberculosis (MICs >100 μg/ml) or were toxic towards mammalian (L6) cells. This is the first report of antiprotozoal activity for natural resin glycosides, as well as for harpagide (4), acetylharpagide (5), tryptophan (6) and buddlejasaponin III (7).     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

The effect of cyanobacteria and azolla on the performance of rice under different levels of fertilizer nitrogen

Cyanobacteria and/or azolla were inoculated, with urea at 0, 72 or 144 kg N/ha, in plots in which azolla-free Indica rice var. IR 28 was grown. Productive tillers, yield and nitrogen contents of grain and straw positively responded to inoculation with cyanobacteria or azolla, even with fertilizer-N up to 144 kg N/ha. Inoculation improved colonization by cyanobacteria. Azolla were superior to the asymbiotic cyanobacteria in enhancing rice performance. Urea at a rate of 72 kg N/ha was found to support the best colonizations when applied with cyanobacteria or azolla or, to give maximum rice yields, both inoculants.